1. Technical Field
The present disclosure relates to a field emission cathode structure and a field emission display using the same.
2. Discussion of Related Art
Field emission displays (FEDs) are a novel, rapidly developing flat panel display technology. Compared to conventional displays, such as cathode-ray tube (CRT) and liquid crystal display (LCD), FEDs are superior in providing a wider viewing angle, lower energy consumption, smaller size, and higher quality.
Generally, FEDs can be roughly classified into diode and triode structures. Diode structures have a cathode electrode and an anode electrode, and are suitable for displaying characters, but not suitable for displaying images. The diode structures require high voltage, produce relatively non-uniform electron emissions, and require relatively costly driving circuits. Triode structures were developed from diode structures by adding a gate electrode for controlling electron emission. Triode structures can emit electrons at relatively lower voltages.
A field emission cathode device includes an insulating substrate, a number of cathodes mounted on the insulating substrate, a number of field emission units a dielectric layer having an upper and lower section, disposed on the insulating substrate, and defining a plurality of voids corresponding to the field emission units, and a number of grids disposed between the upper and lower sections, wherein each grid is secured by the upper and lower sections of the dielectric layer.
In use, the field emission units emit electrons under a voltage between the grids and the cathodes. The emitted electrons pass the holes of grids under the attraction forces of the grids. However, the edge of the upper section of the dielectric layer near the field emission unit will be hit by electrons emitting secondary electrons. The movement directions of the secondary electrons are disorderly so that the boundary of the pixel is unclear. Furthermore, after the secondary electrons are emitted, positive charges are accumulated on the upper section of the dielectric layer. The positive charges can change the electric potential around the upper section of the dielectric layer resulting in difficulty controlling electron emissions movement directions. Therefore, field emission display images using the field emission structure have low resolution.
What is needed, therefore, is a field emission cathode structure and a field emission display using the same with superior display resolution.